Microelectromechanical systems (MEMS) devices are typically fabricated by depositing a plurality of materials layers, some of which are then removed by selective etching during a release procedure. For complex structures, MEMS device manufacture often requires depositing additional patterned films or layers upon a portion of the MEMS device after the initially deposited layers have been released. Such post processing is occasioned due to the limitations imposed on the selection of film materials by the etchant, typically acid, used in the release.
Using conventional photolithographic techniques during such post processing often provides unsatisfactory results. Covering the partially-formed MEMS device with photoresist can damage it. As a result, the ability to add structure to the MEMS device during post-processing is limited. Alternatively, conventional shadow masks can be used to deposit a patterned layer, however, alignment of such masks can be problematic.
As such, there is a need for a MEMS fabrication method that does not limit film composition or MEMS device configuration and avoids alignment problems.